How do wedges help people

Combines a wheel with a central fixed axle which ensures that both must rotate together. A small force applied at the edge of the wheel is converted by rotation to a more powerful force at the smaller axle. This effect can be reversed by applying a large force to the smaller axle resulting in a smaller force at the edge of the larger wheel with much greater rotational speed. The rotation of a threaded shaft can be converted into movement in either direction along the axis of rotation depending on the direction of its spiral thread.

They are commonly used with gears or as a fastening mechanism. Is commonly used to raise or lower heavy objects. Given the friction on the ramp is small, a reduced force is needed to raise a heavy object vertically although it must be moved a greater distance along the ramp to achieve this advantage.

The use of a single fixed pulley and attached cord allows for a change in the direction of the force applied to an object. Although a single overhead pulley provides no mechanical advantage it may be helpful, for example, in allowing a lifting force to be better achieved by redirecting the force down towards the ground to raise an object.

Later students can analyse more complex examples with the purpose of identifying the combination of elements they use in their design. Bring in some tools which are clearly designed with the purpose of increasing the force that can be applied to them bottle opener, crowbar, pliers, car jack and initiate a discussion about what each allows us to do more easily.

Guide this discussion so students become aware of how each is able to magnify the force applied to it. Encourage students to contribute more examples from their own experiences using a screwdriver to get the lid off a paint tin is a good example of an experience many students will have had. Use this to introduce the notion of how levers and other simple machines are used more generally in their lives.

Other simple machines can be introduced one by one by bringing in several examples of each and looking for common features. Steering wheels, screwdriver handles and windlasses are all examples of a wheel and axle; axes, log splitters, tacks and nails are all examples of wedges. The internet has many sites that provide multiple examples of different simple machines. Students explore building a pyramid, learning about the simple machine called an inclined plane. They also learn about another simple machine, the screw, and how it is used as a lifting or fastening device.

Students are introduced to the six types of simple machines — the wedge, wheel and axle, lever, inclined plane, screw, and pulley — in the context of the construction of a pyramid, gaining high-level insights into tools that have been used since ancient times and are still in use today. Students should have a familiarity with the six simple machines and their ability to make work easier, as described in Lesson 1 of this unit, "The Advantage of Machines.

Which of you students truly enjoy lifting or moving heavy objects? Such strenuous work consumes our energy, often leaving us feeling very tired and weary and, sometimes, injured if we lift or move objects improperly.

This unfortunate result is precisely why engineers are continually thinking of ways we can do work easier — so that we can work smarter and not harder. One way engineers accomplish this is by designing machines that help make work easier and more efficient. More specifically, every machine today is comprised of one or more of the six known simple machines — the fundamental components of all mechanical machines.

In this lesson, we will study three of these useful devices in detail: the inclined plane, the wedge and the screw. Although engineers use each of these three simple machines for different purposes, they all operate on the same mechanical principles. Before we go any farther, we need a brief review of the essential principles about simple machines which will prove especially helpful when studying each individual machine. The most important fact is that simple machines never change the amount of work done, only the way in which work is done.

Let's look at the definition of work, which is defined to be the product of force and distance and written mathematically as:. Since the amount of work to be done does not change for a particular chore, this value remains constant. However, both force and distance can in fact be altered.

Simple machines often accomplish work differently by applying the input force, or effort, over a greater distance in order to make work easier to carry out. That is, in order to reduce the amount of force required to do the work, the distance must be proportionately increased.

For example, let's say Emma the engineer needs to do 20 Joules worth of work. She can accomplish this in many different ways, one of which is to exert a force of 20 Newtons over a distance of 1 meter.

However, an easier method may involve the application of a mere 2 Newton force over a distance of 10 meters. In either case, Emma does the same amount of work; however, it is much easier for her to accomplish this by applying less force over a further distance.

Figure 2 illustrates how the same amount of work can be accomplished in many different ways, although some ways are easier — or more efficient — than others. This is the case when using a machine. Figure 2. Equations showing the different ways to achieve the same amount of work. The inclined plane see Figure 3 is perhaps the oldest and most rudimentary simple machine known to engineers.

In fact, many of you are probably wondering how a slanted surface could possibly be classified as a "machine. Figure 3. The inclined plane. The key idea here is that less effort is needed if a load is transferred over a long ramp or inclined path, as opposed to lifting it directly over a vertical path. For example, you may have noticed how movers move very heavy objects, such as a piano, into the back of their moving truck. Obviously, they cannot easily lift such a heavy piece of furniture directly up and into the back of their truck.

Instead, they use a long ramp — or inclined plane — to complete the job. This idea was used long ago by the ancient Egyptians: they used the inclined plane and human strength to erect monumental structures to amazing heights. Even today, engineers employ the inclined plane in many other applications in order to accomplish seemingly impossible tasks. Just a few of these examples include wheelchair ramps, escalators, stairs, highways and even hiking trails, which all rely on the inclined plane as a means of raising heavy objects more easily.

In addition to lifting heavy objects, engineers are also interested in splitting or separating material with as little effort as possible. In this case engineers employ the use of a wedge so that tasks such as chopping firewood, cutting paper, and mowing our yards are made much easier. The wedge, as illustrated in Figure 4, is a simple machine often considered to be a slight variation of the inclined plane since it really consists of two inclined planes set back to back. As a result, one end is thicker than the other so that a sharp cutting edge is formed.

Figure 4. The wedge. While it is true that the wedge is very similar to the inclined plane physically, engineers use this machine for slightly different purposes. The inclined plane functions to transport heavy objects over a stationary surface, while the wedge itself can move in order to move or lift objects. Therefore, the wedge is essentially an inclined plane in motion. When a wedge is moved, a forward force is converted into the outward or parting force used to separate or split material.

Even though the wedge can also be used to lift or move objects a short distance, throughout history it has been primarily utilized as a valuable cutting device. An axe is a classic example of how a wedge is used to make work easier. Can you imagine how hard it would be to cut down a tree or chop wood without an axe?

Even the strongest of men pulling on a piece of timber in opposite directions could not complete the chore. Yet, generally one hefty swing of an axe will accomplish the feat with little effort. In addition to the axe, other familiar tools such as a knife, shovel, plow and scissors all take advantage of the wedge in order to easily separate bound material.

Can you think of other devices where the wedge is at work? Sometimes it is difficult to identify the wedge in the various engineering designs today because of the many different appearances it can have. It is interesting, however, when we realize where the wedge can be found in as many unfamiliar places as well, such as the hull of a ship, airplane wings, and even our front teeth! While all six simple machines have their own distinct qualities, only the screw is able to convert a rotational force into a favorable linear force.

This characteristic is desirable in many engineering applications where rotational motion is the only source of effort available to perform work, like a jet engine.

Similar to the wedge, the screw see Figure 5 is also closely related to the inclined plane since it is actually composed of an inclined plane wrapped around a cylinder. The spiraled edges around the cylindrical surface, commonly referred to as the screw threads, give the screw its ability to do work. Figure 5. The screw. Since engineers can apply this machine to two different unrelated applications, the screw has two general classifications: the fastening screw and the lifting screw.

In contrast to the wedge, which is designed with the ability to cut and separate material, the fastening screw is used to fasten and join two pieces of material together. This type of screw usually has sharp threads which cut into the parts being joined together.

The materials eventually become squeezed and held together between the head of the screw and its threads. Friction from the rough threads, on the other hand, keeps the screw from working loose over time.

There are 6 basic simple machines; the lever , the wheel and axle , the inclined plane , the wedge , the pulley , and the screw. Several of these simple machines are related to each other. But, each has a specific purpose in the world of doing work. But what is work?

Work is the amount of energy necessary to move an object. The further you move it, the more work is required. Work is measured in Newtons. More about that later. First let's look at each of the 6 simple machines in detail. The lever is a long tool such as a pole or a rod put under an object to lift it. The lever is more efficient when combined with a fulcrum. The fulcrum is another object, perhaps a rock, used to brace under the long tool.

This gives the long pole something to push down against. The location of the fulcrum helps determine how well the lever will perform work. The closer the fulcrum is to the object being lifted, the easier the person can lift the object.

The longer the lever, the higher the object can be lifted. Do the math — it's really all in the distance between the object, the fulcrum and the lever. Levers are all around us. Some examples of levers are: door handles, the claws of a hammer for removing nails , crowbars, light switches, bottle openers and hinges. The wheel has always been considered a major invention in the history of mankind.

But it really would not work as well as it does had it not been for the axle. An axle is a rod or pole centered in the wheel that allows the wheel to turn around it. The wheel then spins in a balanced circle to be used as transportation on a bike or to turn the hands of a clock.

Gears are a form of the wheel and axle. Wheels are found where things turn in a circle such as an electric fan, a motor, a revolving door, a merry go round, and any wheel — on the car, on your skateboard, or on a bicycle.

The inclined plane is simply a ramp. One end is higher than the opposite end. This allows things to go from a low point to a higher point. Or vice versa. It takes the same amount of work, but less force, to move an object up a ramp than to move it vertically. Gravity makes it easier to move an object down a ramp than up that ramp.

Ramps are used in skateboard parks, wheelchair ramps and to get heavy equipment in and out of the back of trucks. But a modified version of a ramp is also found in stairs, escalators, ladders, walking paths, even chutes used for dropping your mail into the mailbox. Some people might see the wedge as just an inclined plane, although it is actually two inclined planes.

However, the use of a wedge is actually different in nature. The wedge is used to separate an object apart. This is needed to cut, tear or break something in two. A wedge can also be used to keep things together or secure things from movement.